Properties of masonry mortars manufactured with fine recycled concrete aggregates

• Properties of masonry mortars made with recycled concrete aggregates were studied.
• A cement-to-aggregate ratio of 1:7 and pozzolanic cement CEM-IV was used.
• Five replacement ratios in volume were evaluated: 0%, 5%, 10%, 20% and 40%.
• Replacement ratios up to 40% are a viable alternative for masonry mortars.
• Workable life and water vapour permeability were the most critical properties.

This research evaluates the short- and long-term properties of masonry mortar manufactured with different replacement ratios of natural sand by fine recycled concrete aggregates. The recycled materials were collected from a recycling plant and after passage through a 4 mm sieve, were directly used to make the mixtures, maintaining their original particle size distribution. A pozzolanic CEM-IV/A (V) 32.5 N, with 29% fly ash in its compositions, was used at a 1:7 volumetric cement-to-aggregate ratio. Five mortars with different replacement ratios by volume were tested: 0%, 5%, 10%, 20% and 40%. The data were analysed using one-way analysis of variance to determine whether the “replacement ratio” had a statistically significant effect on the different fresh and hardened properties. DRX and electron microscope techniques were used to examine the morphologies and evolution of the main mineral phases over time during a curing period of 180 days. The results proved that a replacement ratio of up to 40% is a viable alternative for producing environmentally friendly masonry mortar.